Integrated circuits are made by forming on a semiconductor substrate layers of conductive material that are separated by dielectric (insulation) layers. Vias and/or trenches are etched in the dielectric layers and are filled with a conducting material to electrically connect the separated conductive layers. The vias and/or trenches filled with the conductive materials may be referred to as interconnects.
Photoresist materials have wide use in the semiconductor fabrication industry including masking and defining particular regions or areas on substrates or layers. Sacrificial materials have been used in making a lithographic process more uniform and efficient in the semiconductor fabrication industry. Sacrificial materials and photoresist have been used in the fabrication of semiconductor devices, for example, in dual damascene metal interconnects as sacrificial via fill material and mask for lithography process. Dual damascene metal interconnects may enable reliable low cost production of integrated circuits using sub 0.25 micron process technology. Before such interconnects can realize their full potential, however, problems related to the process for making them must be addressed. One problem involves the lithography for defining dual damascene vias and trenches. Sacrificial materials and photoresist materials are used throughout the lithography processes. The ability to remove these materials is crucial for the semiconductor processing. After the vias and trenches are formed, the sacrificial materials and the photoresist materials need to be removed without removing other layers of the device, e.g., without removing or affecting the dielectric layer and/or the surface of the silicon substrate. Additionally, photoresist materials have been used in ion implantations for making source/drain regions and/or source/drain extensions for various devices. After the source/drain regions and/or source/drain extensions are created, the photoresist materials need to be removed without affecting the substrate or other layers on the substrate.
Another problem relates to the selectivity of certain materials, which are used to make semiconductor devices and/or dual damascene devices, to the etch chemistry used to etch the vias and trenches. At times, it's crucial to remove a particular layer while not affecting another layer. Another problem yet, relates to removing the sacrificial materials and/or the photoresist materials used during processing.